What is the meaning of "fine-tuned"?

What does "reach out to" mean?

"Reach out to" means to try and get into contact with someone; to offer help and support to someone. Ex: I tried to reach out to her, but she didn't want my help.

What does file down something mean?

"File something down" means to rub something with an abrasive surface to smooth it out and diminish the size of it. Ex: I filed down my fingernails, that's why they're short.

Can I say "will" instead of "can" here without changing the context?

"Can" and "will" mean different things. "Can" is used to say that one has the ability to do something, whereas "will" is used in the future tense to express something in the future. Thus, "you will see how beautiful it is" expresses that the action will definitely happen in the future. It's different from "you can see how beautiful it is," which means that anyone is able to see its beauty. Ex: I can ride a bike without my hands. (ability) Ex: I will go to my sister's house tomorrow. (future tense)

What's "share feeling" mean? Is this a commonly used expression?

Yes, to "share feelings" means to have the same feelings or thoughts about something, to feel the same way. If you share feelings with your crush, it means that you both like each other. This expression doesn't always have to be used in the romantic way. Ex: He doesn't share my feelings about work. He hates his job. Ex: I really like you. I was wondering if you shared my feelings?

What is the meaning of "a world of difference"?

"A world of something" means a very large amount of something. So 'a world of difference' is a way to emphasize how big of a difference there is. Ex: The island is a world of brilliant colors and dramatic sunsets.